This invention relates to a printer. More particularly, the invention relates to a print engine for a printer.
Pagewidth printheads have the advantage of being able to print rapidly but are constituted by a very large number of nozzles. Should any of these nozzles be defective, an inadequate print quality may result.
According to the invention there is provided a print engine for a printer, the print engine including:
a first printhead;
a second printhead, both printheads including a plurality of inkjet nozzles, the printhead being matched so that defective nozzles in one printhead are substituted by corresponding non-defective nozzles in the other printhead; and
a transfer roller displaceable into abutment with the printheads when no printing is occurring for inhibiting evaporation of ink from the printheads.
Preferably, each printhead is a pagewidth printhead. The printheads may be arranged side by side in spaced, parallel relationship.
In this specification, unless the context clearly indicates otherwise, the term xe2x80x9cpagewidth printheadxe2x80x9d is to be understood as a printhead having a printing zone that prints one line at a time on a page, the line being parallel either to a longer edge or a shorter edge of the page. The line is printed as a whole as the page moves past the printhead and the printhead is stationary, i.e. it does not raster or traverse the page.
The print engine may include a transfer roller rotatably arranged adjacent the printheads for transferring ink from the printheads to media passing the roller, the printheads being arranged in circumferentially spaced relationship relative to, and adjacent, the roller, with the printheads extending parallel to a rotational axis of the roller.
The print engine may include a cleaning station for cleaning a surface of the transfer roller.
In addition, a drying means may be arranged downstream of the roller. The drying means may be an infrared drying lamp.
In a preferred embodiment of the invention, the printheads may share a common ink supply.
As described above, it is possible to obtain defective nozzles in the manufacture of the printheads. Thus, the printheads, at the time of manufacture, may be characterised and matched so that no two corresponding nozzles of the paired printheads are both defective.
A defect list, which may be in the form of a characterisation vector, may be provided for providing an indication of which nozzle of a matched pair of nozzles of the printheads is to be used. The characterisation vector may be encoded and incorporated in the print engine. The print engine may comprise a cartridge housing the printheads and the other components. In a preferred embodiment, the characterisation vector may be retrievable via a barcode applied to the cartridge.
The invention extends also to a printing station for a printer, the printing station including
a first print engine as described above; and
a second print engine, also as described above, arranged in opposed, aligned relationship, with the transfer rollers of the print engines abutting against each other to effect printing on both surfaces of a sheet of print media passing between the transfer rollers.
Preferably, the printheads of both print engines receive ink from a common ink supply. Thus, the printing station may include the ink supply, the ink supply comprising a plurality of separate ink cartridges, each of a different color, to provide for color printing.
The printing station may include an ink reservoir associated with each ink cartridge so that, when an ink cartridge is mounted on its associated reservoir, an interior of the cartridge is in fluid flow communication with the reservoir via a valve arrangement.
The second print engine may be displaceably arranged relative to the first print engine for enabling access to be gained to a print media path defined between the print engines.